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#include <bits/stdc++.h>
#define all(vec) vec.begin(),vec.end()
#define CLR(i,a) memset(i,a,sizeof(i))
#define fi first
#define se second
#define pb push_back
#define SZ(a) ((int) a.size())
#define FOR(i, a, b) for (int i = (a); i <= (b); ++i)
#define ROF(i, a, b) for (int i = (a); i >= (b); --i)
#define getFro(vec) (vec.empty()?0:vec.front())
#define getBac(vec) (vec.empty()?0:vec.front())
#define debug(var) cerr << #var <<":"<<var<<"\n";
#define DEBUG(variable) \
do { \
std::cerr << #variable << ":"; \
for (const auto& elem : variable) { \
std::cerr << elem << " "; \
} \
std::cerr << "\n"; \
} while (0)
#define uniVec(var) \
do { \
sort(var.begin(),var.end());\
var.resize(unique(var.begin(),var.end())-var.begin());\
} while (0)
#define debugN(var,N) \
do{ \
std::cerr<<#var<<":"; \
FOR(i,1,N){ \
std::cerr<<var[i]<<" "; \
} \
std::cerr<<"\n"; \
}while(0)
#define debugMap(variable) \
do { \
std::cerr << #variable << ":\n"; \
for (const auto& pair : variable) { \
std::cerr << " " << pair.first << " => " << pair.second << "\n"; \
} \
std::cerr << std::endl; \
} while (0)
#define lson(var) (var<<1)
#define rson(var) ((var<<1)+1)
#define vecMxx(vec,x) (vec.end()-lower_bound(all(vec),x)) // vec中大于x的数有几个
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef __int128 i128;
typedef pair<ll,ll> pll;
typedef array<ll,3> arr3;
typedef array<ll,2> arr2;
typedef double DB;
typedef long double LD;
typedef pair<DB,DB> pdd;
typedef pair<ll,bool> plb;
constexpr ll MAXN=static_cast<ll>(1e6)+10,INF=static_cast<ll>(1e18)+3;
constexpr ll mod=static_cast<ll>(1e9)+7;
constexpr double eps=1e-8;
ll N,M,Q,X,K,lT,A[MAXN];
/*
*/
struct seqAuto{ // 子序列自动机 subsequence automaton
// 可以处理大小写字母，数字，但是可能要改一下base以及next
vector<vector<int>> next;
// 从i位置开始，字符下一次出现在哪个位置（下标）(包括i位置)
char base='a';
seqAuto(const string &s){
next.assign(SZ(s)+5,vector<int>(28,-1));
ROF(i,SZ(s)-1,0){
FOR(j,0,26){
next[i][j]=next[i+1][j];
}
next[i][s[i]-base]=i;
}
}
inline bool isFind(const string &s){ // 传入substr时，必须为const属性
ll idx=0;
FOR(i,0,SZ(s)-1){
if(next[idx][s[i]-base]!=-1){
idx=next[idx][s[i]-base]+1;
}else{
return false;
}
}
return true;
}
};
inline void solve(){
string S,T;
cin>>S>>T;
seqAuto sat(T);
ll bp=0;
vector<string> ans;
S+=('z'+1);
FOR(i,0,SZ(S)-1){ // 双指针
FOR(j,bp,SZ(S)){
assert(j>=i);
ll len=j-i;
if(!sat.isFind(S.substr(i,len))){ // pos,len
bp=j;
if(ans.empty() || len-1>SZ(ans.back())){
ans.clear();
ans.pb(S.substr(i,len-1));
}else if(len-1==SZ(ans.back()) ){
ans.pb(S.substr(i,len-1));
}
break;
}
}
}
sort(all(ans));
cout<<ans[0]<<"\n";
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin>>lT;
while(lT--){
solve();
}
// solve();
return 0;
}
/*
AC
https://www.luogu.com.cn/record/218545015
*/
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